Different manufacturing processes are known in the production of film bags. With a form-fill-and-seal method (FFS), a bag film is formed into a tube that is converted directly into individual bags that are filled and sealed.
Further known are prefabricated film bags that are manufactured in different ways. Correspondingly, the entire film bag can be formed from a single strip of film by folding and welding.
The present invention, however, relates particularly to film bags that are manufactured by a transverse method, and where the front and back panels are formed of separate sections of film.
U.S. Pat. No. 7,331,917 describes a method of making film bags where a bag strand is formed in such a manner that consecutive film bags are juxtaposed next to each other at longitudinal edges of the bags. The production direction therefore corresponds to a transverse direction with respect to the individual bags. EP 1 541 332 discloses that a bag strand is formed in a first step with consecutive bag blanks that are still connected to each other during production. A first strip of film is supplied in the production direction. A piece of film is then added, and the edges of the piece of film are folded over onto a center section. The edges are usually of equal width leaving a gap between the two edges after the folding step.
Subsequently, pieces of the film are laid evenly spaced transversely relative to the production direction, meaning along the longitudinal direction of the bag, onto the first strip of film prior to a second strip of film being added in the production direction, and the first strip of film and the pieces of the film are covered up. Longitudinal welds are then created transversely relative to the production direction to weld the piece of films, on the one hand, to the folded over edges on the second strip of film and, on the other hand, on the opposite side thereof, to the first strip of film.
Finally, individual film bags are separated from the correspondingly formed bag strand by cutting at the piece of film in such a manner that one folded piece of film forms two folds of consecutive film bags. Film bags thus formed have a single compartment forming a pouch.
U.S. Pat. No. 2,805,814 discloses a compartmented bag that can be formed from a continuous strip of film. The edges of the strip of film can be folded over, and two longitudinal welds are formed at the overlap. The two pouches can optionally each have a side gusset panel. The compartmented bags suffer from the disadvantage that they are hard to handle. In particular, the two individual pouches cannot be stood up.
Another compartmented bag is known from DE 90 006 144, where the compartmented bag is constituted only of a front and a rear panel. A separation of the two pouches is not easily possible, and handling is generally difficult.
GB 937,956 discloses a method of making a string of bags that allows for tearing off individual bags. When the bag film is folded onto itself, a strand of bags can be formed that are adjacent to each other. However, if two webs of material are welded together, it is possible for open bags to be formed in succession, one behind the other as well as one next to the other.